As is well known in the art, wireless packet communications services, such as HyperText Transfer Protocol (http), voice over IP or video streaming, require that packets are received by a destination device within a certain time limit (referred to as a delay budget). For example, one widely accepted delay for voice services (e.g., voice over IP) is 200 ms. In order to meet this end-to-end delay requirement, the access points (for example base stations) to which the destination node is connected need to meet a certain delay limit based on a per flow basis. One problem, however, is that the delay experienced by a packet as a result of being transmitted from a source (e.g., a computer) to an access point over a network (e.g., the Internet) is unknown. Currently this external network delay is accounted for by assuming a worst case scenario (e.g., 150 ms) or assuming a certain requirement for the delay statistics for all the users and packets. For purposes of scheduling packets for transmission over the wireless link to a destination device, the worst case scenario approach sets the delay budget in the access point to the difference between the total acceptable delay for a given data flow and the external network delay (e.g., 50 ms). Some packets may arrive at a receiver side earlier than the delay limit. For the streaming services, however, there is an additional requirement that data packets be delivered to the destination in regular time intervals. This is currently addressed by having a jitter buffer to deliver the packets in order and in regular intervals by delaying the packets arrived earlier. This results in an inefficient use of resources at the access point and impacts capacity of the wireless access system significantly.
FIG. 1 illustrates a conventional commutations network system which utilizes a fixed delay budget scheme. Referring to FIG. 1, a node 4 is connected to a wireless node 6, such as a wireless edge router, a base station controller (BSC) and a base station (BS), through a wireless link. End users (source) 8 are connected to the wireless node 6 through a network 10 (e.g., the Internet). The network 10 may be a wireless network or a wireline network. Network delay Y0 for the network 10 depends on where end user/host located what network he/she/it is connected to, traffic congestion etc, and changes with time. Nevertheless, a fixed wireless delay budget Z0 for the link between the node 4 and the wireless node 6 is set as Z0=D-Ymax where D is an end-to-end delay requirement and Ymax is a network delay for the worst case scenario.
This impacts capacity significantly since packets which arrive earlier than the budgeted time are also sent with the smallest target delay (hence a larger amount of resources). For example, in order to meet an end-to-end delay budget of 200 msec, a tight over the air scheduling delay budget of 50 msec may be required for each packet, if the worst case total delay over the network and over the backhaul (including framing delays) is assumed to be 150 msec.
Therefore, it is desirable to provide a method and system for scheduling packets, which is enable to efficiently use resources and capacity of a network.